Colorado River Basin

The Colorado River flows for approximately 1,450 miles and provides water to seven states in the Western U.S. that are part of the Colorado River Basin. Divided into two regions; the Upper Basin includes Colorado, New Mexico, Utah, and Wyoming; and the Lower Basin includes Arizona, California, and Nevada. It also provides water to Mexico. Colorado receives 40% of its water supply from the Colorado River. It runs through the Rocky Mountains and into the deserts of the Southwest and provides a critical natural resource for agriculture, municipalities, outdoor recreation, hydropower generation, Tribal Nations, and drinking water for several of the country’s largest cities including Denver, Phoenix, and Los Angeles.

As the Southwestern U.S. continues to face compounded severe drought years, leading to less water available to use, Colorado and the other Basin states are working together to create solutions to our water supply and demand challenges proactively. This includes negotiating a post-2026 river operations agreement while working within the existing legal framework, and investigating new tools to better prepare for any future uncertainties.

Below are some of the laws, agreements, decrees and regulations that govern river operations between the Upper and Lower Basins and Mexico, allow for the development of water supplies and storage to meet Compact obligations, generate hydropower, and coordinate operations of major storage facilities in the Basins:

See Laws, Agreements, Decrees, Regulations

• Colorado River Compact (1922)


• Boulder Canyon Project Act (1928)


• Mexican Water Treaty (1944)


• Upper Colorado River Basin Compact (1948)


• Colorado River Storage Project Act (1956)


• Arizona v. California (1963)


• Colorado River Basin Project Act (1968)


• Long-Range Operating Criteria (1970)


• Interim Surplus Guidelines (2001)


• Interim Guidelines for Lower Basin Shortages and Coordinated Reservoir Operations (2007)

In May 2019, the Department of the Interior, Bureau of Reclamation, and all seven Basin states signed a historic agreement called the Drought Contingency Plan (DCP) with the goal of reducing risks associated with drought - including risk of reaching critical reservoir levels in Lake Powell and Lake Mead. Specifically this DCP is designed to address drought-related issues such as drinking water supply, irrigation, power production, environmental preservation (healthy river flows), and overall sustainability of our water resources.

Learn more about the related concept, Demand Management.

Learn more about the Colorado River operations (as determined by the Upper Colorado River Commission) at the Commissioner's Corner.